Google has slowly but surely been marching toward a new extension platform called Manifest V3 for Chrome. And now there is a firm timeline for its rollout. Starting with Chrome 112 in January of 2023 the company may start turning off support for Manifest V2 in the Canary, Dev and Beta channels. Then in June with Chrome 115, it will begin experimenting with turning off support in the stable channel as well.
To coincide with the transition of Chrome stable to V3, all Manifest V2 extensions in the Chrome Web Store will be switched to unlisted. And eventually in January of 2024, the remaining V2 extensions will be removed completely.
The transition has not been without controversy, however. While Manifest V3 includes a ton of changes, many of which Google claims are in the name of privacy and security, it's draw particular ire for how it would affect ad-blockers. It would essentially prevent them from working as they currently do, and render them all but useless.
Most modern ad-blockers like uBloc Origin and AdGuard rely on Chrome’s “webRequest” API to block entire categories of HTTP requests from being made. But this method can add significant delays to load and render times for sites, which Google is obviously eager to avoid. Instead, Manifest V3 requires developers to use a “declarativeNetRequest,” which essentially forces them to use a blocklist of specific URLs. The problem is that list of "rules" is limited to 30,000 entries. And many ad-blocking lists can be in excess of 300,000 entries.
Enterprise users are at least getting some reprieve, and will be able to continue using Manifest V2 extensions until January of 2024.